# This is the code that works
$mydata = [["Item",     "Category", "Price"], 
           ["Nails",    "Hardware",  "5.25"],
           ["Shirt",    "Clothing", "23.00"]];

# Write all the data at once...
$rng = $xlBook->ActiveSheet->Range("A1:C7");
$rng->{Value} = $mydata;

# This is my code that doesn't work because I changed it to an array.
@mydata = ("Item",     "Category", "Price", 
           "Nails",    "Hardware",  "5.25",
           "Shirt",    "Clothing", "23.00");

# Write all the data at once...
$rng = $xlBook->ActiveSheet->Range("A1:C7");
$rng->{Value} = @mydata;